Artificial foot, joint, and ankle



NOV, 2, 1937, L. H. SIMONVSSON 2,698,067

ARTIFICIAL FOOT, JOINT, AND ANKLE Filed May 28', 1935 %Am $Wm Patented Nov. 2, 1937 UNITED STATES PATENT Application May 28, 1935, Serial No. 23,833 In Great Britain July 4, 1934 3 Claims.

The invention herein considered consists of an artificial foot, joint and ankle, designed for fulfilling the principal functions of a natural foot.

The inconveniences attached to existing arti- 5 ficial feet, are due to the fact that the lateral movements of the foot depend on rubber bearings whose effect is not satisfactory, the rubber becoming compressed by the load, and the sideways movements being thus impeded, as also the 10 leg shortened, added to which this bearing has a short durability.

In the present invention the above said inconveniences are eliminated, thanks to the fact that the load goes over to the foot through a 15 ball-bearing device.

The foot in the present invention has been designed for such movements of the joint as to allow the weight of the body, even when moving upon irregular ground, to be evenly distributed 20 over the whole treading surface of the foot, the foot always putting itself in the same angle as the underlying ground. This design is of great importance even when moving upon a regular horizontal ground, considering that when the 5 weight of the body is transmitted from one leg to the other a certain lateral movement is required to preserve the equilibrium of the body. For this purpose it appears necessary that the joint should be designed in such a manner as to allow the foot 3 to move in various directions in relation to the leg. This is made possible by the fact that the jointin this case a ball-bearing joint-has a spherically shaped outer ring, that the foot as well as the lower end of the leg are designed so 35 as to allow a sideways inclination of the foot (valgus and varus position), that any lateral turning of the foot to the left and to the right in relation to the leg is excluded, and that those 'parts of the leg and the foot which touch one an- 40 other when taking over the weight of the body, are shaped so as to exclude any sideways break.

The invention is illustrated by the enclosed drawing, in which Fig. 1 shows a foot joint from the side,

45 Fig. 2 shows a corresponding vertical section cut across the ball bearing, and

Fig. 3 shows a corresponding vertical section cut in front of the ball bearing.

In the drawing, 1 indicates an artificial foot 50 which, in the invention, is attached to the lower part of an artificial leg 3 by means of a spherical (universal) joint 2. In the design illustrated by said drawing, the joint 2 consists of a ball-bearing device, in the inner ring 4 of which a bolt 5 is 5 located, with both its ends reposing in cylindrical sleeves B and 1, which are rigidly attached to the foot I by means of radially projecting screw bolts 8 and 9. The outer ring it of the ballbearing has a spherical trace l5, and is provided with a radially projecting screw bolt, by means 5 of which it is rigidly attached to the lower part 3 of the leg.

In order to limit the inclining sideways movement of the leg in relation to the foot, as also to contribute to the support of the weight of the 10 body, the leg is provided on each side of its lower end with recess having on its upper end an obliquely disposed rounded supporting surface I I, which should repose upon the supporting sleeve of the joint when the leg reaches its largest sideways inclination. The sideways surfaces l 4 of the recesses, which continue the supporting surfaces downwards, are parallel to each other and run in the longitudinal direction of the leg. When the leg inclines sideways, in or out, the sideways surfaces of the recesses serve as a steering trace for the sleeves in their various positions, thus preventing all lateral turning of joint and foot to the left and to the right in relation to the leg.

In order to contribute to the support of the weight of the body, as also to limit the tilting movement of the foot upwards in a vertical direction towards the leg, the lower part 3 of the leg in front of the ball-bearing is provided with a projection l2 (Fig. 3) rounded on both sides of its lower end, which projection enters in and rests against a corresponding recess 13 in the foot.

I do not wish to be limited as to details of construction, as these may be modified in many particular parts without departing from the spirit of my invention.

I claim:

1. An artificial foot, joint and ankle provided with a ball bearing device placed between the foot and the lower end of the leg, the ball bearing having an outer ring with a spherically shaped outer ball race and an inner ring with an inner ball race, characterized thereby, that the inner ball race ring is secured to a bolt extending into and being secured in two supporting sleeves, which by means of screw bolts are secured to the foot, the outer ball race ring being secured to the lower part of the leg by means of a screw bolt.

2. An artificial foot, joint and ankle provided 5 with a ball bearing device placed between the foot and the lower end of the leg, the ball hearing having an outer ring with a spherically shaped outer ball race and an inner ring with an inner ball race, characterized thereby, that the inner ball race ring is secured to a bolt extending into and being secured in two supporting sleeves, which by means of screw bolts are secured to the foot, the outer ball race ring being secured to the lower part of the leg by means of a screw bolt, and characterized further by the fact, that supporting surfaces are furnished at the inand outside of the lower end of the leg, which surfaces at the top are so shaped that the cylindrical supporting sleeves fit into them and which surfaces downwards in the longitudinal direction of the leg are extended on both sides of the supporting sleeves in order to prevent the clockwise and counter clockwise rotary motion of the sup porting sleeves and the foot, when looking in the longitudinal direction of the leg.

3. An artificial foot, joint and ankle provided with a ball bearing device placed between the foot and the lower end of the leg, the ball bearing having an outer ring with a spherically shaped outer ball race and an inner ring with an inner ball race, characterized thereby, that the inner ball race ring is secured to a bolt extending into and being secured in two supporting sleeves, which by means of screw bolts are secured to the foot, the outer ball race ring being secured to the lower part of the leg by means of a screw bolt, and characterized further by the fact, that supporting surfaces are furnished at the inand outside of the lower end of the leg, which surfaces at the top are so shaped that the cylindrical supporting sleeves fit into them and which surfaces downwards in the longitudinal direction of the leg are extended on both sides of the supporting sleeves in order to prevent the clockwise and counter clockwise rotary motion of the supporting sleeves and the foot, when looking in the longitudinal direction of the leg, and characterized finally by this, that the lower end of the leg in front of the ball bearing is provided with a downwards projection, rounded in longitudinal direction towards the foot and fitting into a corresponding recess of the foot.

LUDVIG HJALMAR SIMONSSON. 

